KR20130103770A - Alkali-free glass for flat panel display and melting process thereof - Google Patents

Abstract

In the present invention, an alkali free aluminoborosilicate glass and a melting process thereof for a flat panel display are disclosed. The glass comprises 54-68% SiO ₂ , 10.8-17.1% Al ₂ O ₃ , 7.6-12.5% B ₂ O ₃ , 0.2-1.8% MgO, 4.2-15% CaO, 0.6-7.1% SrO, 0.1-5% BaO, 0.2-1% ZnO, 0.01-1.54% ZrO ₂ and 0.1-1.3% SnO + SnO ₂ . The aluminoborosilicate glass of the present invention does not contain arsenic and antimony which can cause serious pollution to the environment, and the gas inclusion content in the glass is reduced by a predetermined process to improve glass quality.

Description

Alkali-free Glass for Flat Panel Display and Melting Process Thereof}

FIELD OF THE INVENTION The present invention belongs to the technical field of glass and relates to alkali-free aluminoborosilicate glass, and more particularly to aluminoborosilicate glass for flat panel displays.

Liquid crystal displays (LCDs) are formed by interposing a liquid crystal between two glass substrates, and apply a voltage to implement a display. The glass substrate has two functions, firstly, to keep the liquid crystal at a specified thickness; Secondly, it contains transparent electrodes and switch elements necessary for driving. There is a space between the two glass substrates, which has a rigid dimension of 5-10 μm.

In response to the development of LCD technology, various glass substrates having different compositions and physical properties and prepared by different methods are provided. LCDs have very high requirements for the properties of glass substrates and LCD flat panels. The requirements for LCD glass substrates are as follows.

First, there is a requirement for accurate dimensions: The manufacturing process of high performance displays involves repeated precision photolithography, and the machining accuracy of the outer dimensions of the substrate is required to be 1/10 mm. Most importantly, the requirements for surface flatness and thickness are very stringent. If the accuracy of the two substrates of the active matrix LCD is not guaranteed, the full space (space between the two substrates) will have a local error, which will directly affect the electric field and the pixels, resulting in uneven grayscale and color. Substrates with low flatness also cause problems in the photolithography process, for example, light may not concentrate on the entire surface and defects may occur in the electrical circuit. When using proximity printing, the warped substrate may damage the photomask. Variations in the flatness of the substrate include simple warpage, wavy patterns of the entire substrate, and roughness in nanometer molecular units.

Second, there is a requirement for thermal resistance: thermal resistance is mainly related to temperature properties and heat shrinkage, with an internal connection between them. In the process of manufacturing a thin film transistor (TFT), the substrate is repeatedly subjected to heat treatment. LCDs of the p-SiTFT type can be heated to 625 ° C during preparation, and the substrate is required to maintain rigidity even at this temperature without viscous flow. If not, the glass is distorted during cooling resulting in dimensional change as well as thermal stress. Glass has this property only below the strain temperature T _st . Thus, the T _st of such glass substrates should exceed 625 ° C., and if added for 25 ° C., the T _st of such glass substrates should be at least 650 ° C. or higher. It has been found that the substrate still exhibits dimensional change even under T _{st due to} structure relaxation.

The display undergoes repeated and rapid temperature rises and drops several times during the manufacturing process, which inevitably leads to structural relaxation and dimensional change of the glass substrate, leading to variations in the electronics for photolithographic flat panel manufacturing. Therefore, the shrinking dimension of the entire substrate component needs to be a small part of the width of the thinnest line in the circuit, i.e. several microns. For displays with dimensions of hundreds of millimeters, the amount of shrinkage allowed is only a few million. Lines in circuits are getting thinner and thinner to improve resolution, but displays are getting bigger and bigger. Automatic compensation techniques can compensate for thermal shrinkage during the photolithography process, but low thermal shrinkage is still required.

Third, there is a requirement for chemical stability: the substrate glass must be able to withstand the various chemical treatments in the display manufacturing process. For example, an α-Si active matrix LCD has more than seven thin film circuits, and thus requires a number of corrosion steps corresponding to the number of layers. Caustic and detergents range from strong acidic to strong alkaline, such as more than 10% NaOH, more than 10% H ₂ SO ₄ , concentrated HNO ₃ , 10% HF-HNO ₃ , concentrated H ₃ PO ₄ and the like. The chemical stability requirements for substrates are one of the most stringent requirements for all types of glassware.

Fourth, there is a requirement for surface defects and internal defects: substrates should have high surface quality and internal quality, and there should be no scratches or stains on the edges and surfaces of the fabricated circuits. Defects should be less than a few microns to prevent circuit damage. Internal bubbles and inclusions are acceptable if they are a small fraction of pixel size, for example a display with a 100 μm pixel dimension may contain inclusions of 50 μm dimensions and the maximum allowable limit of defect area is 25 of a single pixel area. % to be.

Fifthly, there is a requirement for alkali limitation: in the manufacturing process of high matrix LCD, the temperature of heat treatment is less than 350 ° C., soda lime glass substrate can be used. A method of plating Na sintering layer of SiO _{2 on} the surface to prevent Na ⁺ from moving into the circuit is widely used. However, if the temperature of the heat treatment is close to T _st , the intervening layer hardly prevents Na ⁺ from moving. In non-native matrix LCDs (active matrix LCDs), the heat treatment temperature is very high due to the manufacture of α-Si or p-Si devices on the substrate, especially in p-Si devices with higher heat treatment temperatures than in the case of α-Si devices. Do. The heat treatment temperature mainly depends on the process of manufacturing the TFT element. Since the plating of the gate dielectric SiNx requires a high temperature of more than 600 ° C. and Na ⁺ from the substrate can pass through the tidal layer at this time, the LCD substrate in this manner is as low as possible, and preferably reaches zero alkali. Should have content.

U.S. Pat.Nos. 5811361, 5851939, 6329310 and the like mention that substrate glass for TFT-LCDs should have the following basic physical properties:

1. In the glass substrate for TFT-LCD, the coefficient of thermal expansion of glass should be sufficiently low in order to reduce the damage caused by expansion by heating and shrinkage by cooling according to the manufacturing temperature of the substrate, and generally 40 × 10 ^-7 / Should be ℃.

2. In the glass substrate for TFT-LCD, in order to reduce the volume shrinkage and dimensional instability caused by repeated heating depending on the manufacturing temperature of the substrate, the strain point of the glass must exceed at least 650 ° C.

3. In order to meet the growing demand for lightweight flat panel displays, the density of glass should be less than 2.6 g / cm ³ , the lighter the better.

In addition, as LCDs develop toward the large dimensions, high image quality, high brightness, and the like of LCDs to meet market demand, TFT-LCD liquid crystal glass substrates need to have better performance.

The LCD provides the display using a "back-permeable" irradiation mode. Since the utilization rate of the light of the backlight is not high, the luminous intensity is inferior to that of CRT, PDP and OLED. Increasing brightness has always been the direction of LCD development. Therefore, the increase in the light transmittance of the glass substrate can lead to a better function. At present, the light transmittance of major glass substrates has reached 90%.

As the size of the LCD increases, the area of the glass substrate also increases in order to reduce production costs. Substrates less than 1 mm in thickness and larger than 1 m ² can be easily implemented, and some manufacturers even implement substrates larger than 6 m ² . Such thin glass substrates are easily broken during use and transportation, and the glass is sag due to gravity. The problem of sagging of thin and wide substrates causes difficulties in the manufacture of the substrates. Therefore, in order to prevent little or no distortion of the glass substrate due to external forces or self-gravity, it is desirable to increase the bending strength of the glass substrate in order to reduce damage to the glass substrate, It is advantageous.

Currently, overflow molding is the most widely used method for producing LCD glass substrates. This is because the glass substrate produced by this method does not require surface polishing for post-treatment. However, this method requires a high level of control of the production process. The flow rate, temperature, and tension of the stretching machine must be precisely controlled simultaneously, and even slight changes can cause excessive tension in the stretching machine and cause the glass substrate to break. If the breakage of the glass substrate occurs, it takes a long time to deliver the substrate again, etc., which reduces the production efficiency and yield of good products. Therefore, high bending strength is also required for LCD glass substrates to prevent breakage of the substrate during the process of overflow molding.

In recent years, due to the trend toward larger and larger LCDs, the TFT type of the active matrix LCD is required to be lighter, and the substrate tends to be thinner, so that the strength of the substrate and the reduction of its own load are required to achieve the weight reduction.

In general, alkali-free glass is chosen to achieve the required physical properties in LCD glass substrates, such as coefficients of thermal expansion below 40 × 10 ⁻⁷ / ° C., strain points above 650 ° C., and densities below 2.6 g / cm ^3. Generally belongs to the glass of RO-Al ₂ O ₃ -B ₂ O ₃ -SiO ₂ series.

As the requirements for environmental protection become increasingly stringent, the use of tablets such as As ₂ O ₃ , Sb ₂ O _3, etc. is gradually being restricted. EU countries currently prohibit products containing arsenic from entering the EU market. The present invention therefore focuses on the realization of products that do not contain As and Sb.

According to Stokes Law, the velocity of bubbles rising to the surface in the molten glass is inversely proportional to the viscosity of the molten glass. That is, as V = 2r2g (ρ−ρ ′) / 9η, V denotes a bubble rising speed, r denotes a bubble radius, g denotes a gravitational acceleration, ρ denotes a glass density, and ρ 'denotes a Represents the density of the gas in the bubble, and η represents the viscosity of the molten glass. In order to ensure smooth release of the bubble inclusions, it is preferred that the viscosity of the molten glass is as low as possible, especially at high temperatures.

Gas inclusion (bubble) is a major defect in glass, which comes from a fairly complex source, some of which are air in the space upon batch melting, some of which are gases produced by the decomposition of various compounds, and some of which are reaction vessels. Gas released from a material (eg, a refractory material). Conventionally, such gas inclusions have been removed by using arsenic or antimony as tablets, but they are harmful to the environment and human body. The present invention therefore focuses on the production of glass having a very low content of arsenic and antimony, preferably glass free of arsenic and antimony. The following quantitative indicators of the effect of gas inclusions on product quality are: The content of gas inclusions in commercially produced glass (glass substrates) should be less than one gas inclusion per kilogram of glass (0.5 mm in diameter). Excess gas inclusions are considered defects). For glass weighing 1 kg or more, the indicator is preferably 0.5 gas inclusions per kilogram of glass. For glass weighing 2 kg or more, the indicator is preferably 0.3 gas inclusions per kilogram of glass, the smaller the better.

An object of the present invention is an alkali-free low density, low coefficient of thermal expansion, high strain point, high chemical stability, high bending strength and high light transmittance without containing harmful substances As ₂ O ₃ and Sb ₂ O ₃ ) To provide glass.

In order to realize the above object, the present invention is an alkali free glass for flat panel display, 54 to 68% SiO ₂ , 10.8 to 17.1% Al ₂ O ₃ , 7.6 to 12.5% B ₂ O ₃ , 0.2 ~ 1.8% MgO, 4.2-8% CaO, 0.6-7.1% SrO, 0.1-5% BaO, 0.2-1% ZnO, 0.01-1.54% ZrO ₂ and 0.1-1.3% SnO + SnO An alkali free glass is provided, which is composed of _two . The alkali free glass according to the invention overcomes the deficiencies according to the prior art described above.

The weight ratio of MgO + SrO + BaO in the glass is 0-12%.

The light transmittance of glass is 93-97.

The strain point of glass is 650-685 degreeC.

The coefficient of thermal expansion of glass is 30x10 <^-7> / ^{degreeC-40x10 <-7>} / ^degreeC in the range of ^{0-300 degreeC} .

The liquidus temperature of glass is 1110-1210 degreeC.

The density of glass is 2.300 ~ 2.550 g / cm ³ .

The manufacturing process of the alkali free aluminoborosilicate glass is as follows:

(1) As raw materials for glass, 54 to 67% of SiO ₂ , 13 to 18% of Al ₂ O ₃ , 7 to 12% of B ₂ O ₃ , 0 to 1.8% of MgO, and 3 to 10% of CaO Preparing 0.2-8% SrO, 0.1-7% BaO, 0.001-1.5% ZnO, 0.001-1.0% ZrO ₂ and 0.01-1.0% of a tablet;

(2) reacting the raw material according to step (1) intact for 4 hours in a temperature range of 1500 to 1620 ° C. to obtain a glass solution in the first container of the nonmetallic refractory material and introducing the glass solution into the second container;

(3) keeping the glass solution in the second container at 1640 ° C. for 40-75 minutes and at 1600 ° C. for 40-120 minutes;

(4) The solution obtained in step (3) is introduced into a metal mold and cooled to form a flat plate, followed by annealing, and the thermal expansion coefficient is 28 to 39 × 10 ⁻⁷ / ° C. in the range of 0 to 300 ° C. And an alkali free glass having a density of 2.5 g / cm ³ or less and an elastic modulus of 70 GPa or more.

The alkali-free glass according to the present invention has a light transmittance of more than 93% in the wavelength range of 500 to 650 nm, a bending strength of more than 110 MPa, a strain point of more than 650 ° C., and a thermal expansion coefficient of 28 to 39 at a range of 0 to 300 ° C. × 10 ⁻⁷ / ° C., liquid phase temperature below 1250 ° C., density 2.35 to 2.55 g / cm ³ , modulus of elasticity above 70 GPa, and viscosity above 15000 poise at liquid phase temperature.

In the present invention, by controlling the content of SrO + BaO + MgO and the ratio of CaO / (SrO + BaO + MgO), the bending strength of the glass is more than 110MPa, preferably more than 118MPa, more preferably more than 130MPa To further increase, thereby providing the effect of reducing distortion in the manufacturing process of large glass substrates.

Alkali-free glass according to the present invention has a network structure formed of SiO ₂ , B ₂ O ₃ and Al ₂ O ₃ , SiO ₂ + Al ₂ O ₃ + B ₂ O ₃ ≥80%, ∑RO (R is Mg , Ca, Sr, Ba, and Zn) / Al ₂ O ₃ are 0.9 to 1.2 (weight ratio). Here, Si is the main component of the glass network, Al ^{+ 3} may be introduced into the glass network in the form of a tetrahedron [AlO _4] in the presence of free oxygen supplied by the RO. Si ^{4 +} is incorrectly 4 (tetravalent) and Al ^{3 +} 3 because the (trivalent), when the Si ^{+ 4} is replaced with Al ³⁺ is an imbalance comprises the electrons, thus the metal ions are drawn to the glass network, the network It increases the integrity and strength of the glass, which increases both the viscosity and softening point of the glass.

When free oxygen is deficient, intermediate ions are generally introduced into the network in the following order: [BeO ₄ ] → [AlO ₄ ] → [GaO ₄ ] → [BO ₄ ] → [TiO ₄ ] → [ZnO ₄ ]. Therefore, ΣRO and the condition of (R is Mg, Ca, Sr, Ba, Be , and Zn) / Al ₂ O ₃ is 0.9 ~ 1.2, Al ^{3 +} a tetrahedron when the first meet, B is an [BO3] triangle To form a control and prevent excessively high melt temperatures. ∑RO / Al ₂ O ₃ is preferably 0.9 to 1, more preferably 0.96 to 1, in a preferred embodiment.

In the present invention, the SiO ₂ content is 54-67%. Increasing the SiO ₂ content is advantageous for lightening the glass, lowering the coefficient of thermal expansion and improving the chemical resistance, while increasing the high temperature viscosity, which is disadvantageous in terms of manufacturing. Therefore, the SiO ₂ content is determined to be 54-68%.

The Al ₂ O ₃ content is 13-18%, preferably 15-18%. High Al ₂ O ₃ content is beneficial for the improvement of the strain point and the bending strength of the glass, but excessive Al ₂ O ₃ content will easily cause the crystallization of the glass.

B ₂ O ₃ plays a special role, enabling the individual formation of glass. Under the conditions of hot melting, B ₂ O ₃ is difficult to form [BO ₄ ], as a result of which the high temperature viscosity decreases. At low temperatures, B tends to trap free oxygen to form [BO ₄ ] and prevent crystallization. However, excessive B ₂ O ₃ reduces the strain point of the glass. Therefore, the B ₂ O ₃ content is preferably in the range of 7 to 12%, more preferably in the range of 8 to 12%.

MgO forms the outside of the network, and Mg is introduced into the network and exists in the form of [MgO ₄ ] only when oxides such as Al ₂ O ₃ and B ₂ O ₃ do not exist. Excessive MgO can lead to sparse structures and reduced density and hardness. MgO can also reduce the crystallization tendency and crystallization rate and increase the chemical stability and mechanical strength of the glass. However, the excessive content should not be included, in which case the glass tends to crystallize and the coefficient of thermal expansion is excessively high. Another important role of the introduction of MgO is to compensate for changes in material properties (viscosity-temperature properties) due to an increase in the CaO content in the embodiment of the present invention. The MgO content is 0-1.8%, preferably 0- <1%.

CaO plays a role similar to MgO, and Ca has the effect of forming a denser glass structure. CaO can control and reduce the high temperature viscosity and can significantly improve the melt properties without reducing the strain point of the glass. Excessive CaO can reduce the chemical resistance of the glass. Here, the CaO content is selected in the range of 3 to 10%, preferably in the range of 4 to 9%.

In RO-SiO ₂ -B ₂ O ₃ -Al ₂ O ₃ series glass, the additional effect of CaO is reflected in the effect of the change in the CaO / (SrO + BaO + MgO) ratio on the glass's flexural strength. Ca, Mg, Sr and Ba jointly form a component of the glass as the oxidant RO, and? RO / Al ₂ O ₃ is determined within a predetermined range. If the CaO content is reduced, SrO and BaO must be added to the glass to compensate for the reduced CaO. As the CaO / (SrO + BaO + MgO) ratio changes, the extreme value of the bending strength of glass appears. According to the experiment, the CaO / (SrO + BaO + MgO) ratio is preferably in the range of 0.3 to 6, more preferably in the range of 0.3 to 2, and most preferably in the range of 0.3 to 0.8. Thereby the flexural strength of the glass can be improved to exceed 110 MPa, more preferably above 118 MPa, most preferably above 130 MPa.

Both SrO and BaO have the effect of improving chemical stability and resistance to crystallization, but excessive SrO and BaO can cause an increase in the glass's density and coefficient of thermal expansion. Both SrO and BaO are components with particularly improved chemical resistance, and the total content of both components should exceed 0.2%. It is preferable that the content of SrO and BaO is as high as possible with respect to the improvement of chemical resistance, but the content of SrO and BaO is as low as possible with respect to the density of glass and the coefficient of thermal expansion. Therefore, the content of SrO and BaO will have to be controlled to be within a predetermined range. More specifically, the content of SrO is 0.2-8%, the BaO content is 0.1-7%, but the content of SrO + BaO is in the range of 1-10%, preferably in the range of 2-9%, More preferably it should be controlled in the range of 2-6%.

ZnO can reduce the high temperature viscosity of the glass, improve chemical resistance and reduce the coefficient of thermal expansion. However, excessive ZnO content can reduce the strain point of the glass.

ZrO ₂ can effectively improve the chemical stability of the glass, reduce the coefficient of thermal expansion, and significantly improve the modulus of elasticity. However, ZrO ₂ has a low solubility in glass, which can increase the high temperature viscosity and liquidus temperature of the glass and increase the crystallinity tendency of the glass. ZrO ₂ is also advantageous for improving the acid resistance, elasticity, flexural strength and thermal expansion properties of the glass.

And ^{S 2 - - Fe 3 +,} Cl in the composition of the glass substrates for LCD content will be as low as possible. In the present ^{invention, Fe 3 + <0.3%,} Cl - <10ppm, S 2 - <0.3% , preferably from ^{Fe 3+ <0.1%, Cl -} <10ppm, S 2 - , and <0.1%, more preferably is ^{Fe 3 + <0.05%, Cl} - < is 10ppm, S ^2- <0.05%.

Hereinafter, the present invention will be further described with reference to embodiments. It is to be understood that the examples are used by way of example only and to illustrate the invention, but do not limit the invention in any way.

Embodiments of the invention are shown in Tables 1-3. The amount of each material is as listed in the table, and in each example the total amount of material is about 300 kg. The materials are uniformly mixed and introduced into container 1 of the refractory material. The temperature of Vessel 1 is heated to 1500 ~ 1600 ℃ by Joule heating, but it should not exceed 1620 ℃. After 4 hours of reaction, the materials are introduced into vessel 2 heated to 1640 ° C. by the electrode and kept warm for about 60 minutes, but not to exceed 75 minutes. The temperature of vessel 2 is then reduced to 1600 ° C. and kept for 60 minutes, but not to exceed 120 minutes. After warming, the molten glass is quickly poured into a metal mold and cooled to form a substrate (100mm * 200mm * 10mm) and annealed. Examine the bubble content of the glass samples to obtain physical properties for the elastic modulus, weight loss, flexural strength, strain point temperature, liquidus temperature, stiffness and thermal expansion coefficient of each glass sample.

Example 1 Example 2 Example 3 Example 4 Example 5 Example 6 Example 7 SiO ₂ 54.50 54.50 60.50 61.00 56.20 67.3 58.00 Al ₂ O ₃ 17.10 17.00 12.10 11.90 16.00 10.9 14.00 B ₂ O ₃ 11.00 11.10 10.00 9.58 11.80 8.5 12.50 MgO 1.80 1.70 0.56 0.70 1.20 0.40 1.02 CaO 7.90 7.40 6.70 6.50 6.80 4.6 5.20 SrO 7.10 6.60 4.60 4.20 5.00 2.7 5.20 BaO 0.10 1.30 4.00 4.40 2.09 2.8 2.98 ZnO 0.20 0.00 0.40 0.45 0.32 0.60 0.36 ZrO ₂ 0.10 0.15 0.54 0.62 0.24 1.30 0.30 SnO + SnO ₂ 0.20 0.25 0.60 0.65 0.35 0.90 0.44 MgO + SrO + BaO 9.20 9.60 9.16 9.30 8.30 5.90 9.22 CaO / (MgO + SrO + Ba) 0.88 0.77 0.73 0.70 0.82 0.78 0.57 Light transmittance (T550) 92 95 93 90 93 93 96 Strain point (℃) 638 640 654 656 650 665 652 Thermal expansion coefficient (× 10 ^-7 / ℃) 39.10 39.15 36.21 36.32 38.80 37.60 38.70 Flexural strength (MPa) 116 117 120 119 116 116 123 Liquid Temperature (℃) 1120 1125 1125 1128 1158 1152 1165 Density (g / cm ³⁾ 2.6450 2.6370 2.5520 2.5310 2.5970 2.3620 2.5740 Modulus of elasticity (GPa) 72 72 73 76 70 75 74 Number of bubbles per kg of glass 0.20 0.50 0.30 0.70 0.20 0.80 0.20

Example 8 Example 9 Example 10 Example 11 Example 12 Example 13 Example 14 SiO ₂ 58.30 67.5 67.8 55.00 55.60 61.60 61.00 Al ₂ O ₃ 12.80 12.5 13.2 17.00 16.80 11.50 12.00 B ₂ O ₃ 10.20 8.45 7.6 11.20 11.30 9.40 8.00 MgO 0.46 0.88 0.20 1.40 1.30 0.76 0.80 CaO 8.00 4.9 4.7 7.30 7.00 6.00 15.0 SrO 6.00 1.6 0.6 5.70 5.30 4.10 2.65 BaO 3.00 1.8 2.3 1.60 1.80 4.75 0.10 ZnO 0.39 0.80 0.90 0.30 0.35 0.50 0.30 ZrO ₂ 0.40 1.42 1.50 0.20 0.22 0.69 0.0 SnO + SnO ₂ 0.45 0.15 1.20 0.30 0.33 0.70 0.15 MgO + SrO + BaO 9.46 4.28 3.10 8.70 8.40 9.61 3.55 CaO / (MgO + SrO + Ba) 0.85 1.14 1.52 0.84 0.83 0.62 4.2 Light transmittance (T550) 91 93 93 92.5 93 94 93 Strain point (℃) 648 667 667 645 649 657 646 Thermal expansion coefficient (× 10 ^-7 / ℃) 36.41 36.54 36.51 38.80 38.82 36.25 42.80 Flexural strength (MPa) 120 109 105 118 118 124 101 Liquid Temperature (℃) 1140 1205 1170 1136 1160 1176 1179 Density (g / cm ³⁾ 2.5700 2.3830 2.3820 2.6140 2.6120 2.5200 2.4900 Modulus of elasticity (GPa) 76 73 75 75 76 77 76 Number of bubbles per kg of glass 0.20 0.90 1.10 0.30 0.30 0.40 0.20

Example 15 Example 16 Example 17 Example 18 Example 19 Example 20 Example 21 SiO ₂ 67.0 58.50 67.2 67.4 57.40 59.20 68.0 Al ₂ O ₃ 11.0 12.30 11.5 10.8 14.70 12.50 8.1 B ₂ O ₃ 8.6 10.40 8.9 9.0 12.20 10.00 12.0 MgO 0.45 0.48 0.34 0.35 1.09 0.52 0.16 CaO 4.8 7.80 4.2 5.0 5.60 7.40 4.9 SrO 3.0 5.60 2.6 1.9 5.40 5.20 2.9 BaO 3.0 3.64 2.5 2.6 2.61 3.78 0.1 ZnO 0.55 0.36 0.64 0.70 0.34 0.40 1.00 ZrO ₂ 0.82 0.42 1.20 1.30 0.26 0.47 1.54 SnO + SnO ₂ 0.78 0.50 0.92 0.95 0.40 0.53 1.30 MgO + SrO + BaO 6.45 9.68 5.45 4.85 9.09 9.52 3.15 CaO / (MgO + SrO + Ba) 0.74 0.81 0.77 1.04 0.62 0.77 1.56 Light transmittance (T550) 95 95 92 93 93 94 93 Strain point (℃) 665 649 666 665 650 652 668 Thermal expansion coefficient (× 10 ^-7 / ℃) 37.80 36.38 36.50 36.52 38.74 36.24 36.53 Flexural strength (MPa) 115 114 113 109 118 117 107 Liquid Temperature (℃) 1210 1100 1185 1191 1162 1120 1200 Density (g / cm ³⁾ 2.4900 2.5690 2.3850 2.3830 2.5860 2.5620 2.3810 Modulus of elasticity (GPa) 75 78 76 78 71 75 74 Number of bubbles per kg of glass 0.70 0.30 0.70 0.70 0.20 0.40 0.80

While the present invention has been described in detail with reference to preferred embodiments, it should not be understood that the embodiments of the present invention are limited to the above-described embodiments. Those skilled in the art will understand that various modifications or equivalent substitutions may be made without departing from the spirit of the present invention and such modifications or substitutions fall within the scope of the present invention as defined by the appended claims.

Claims (8)

Alkali-free glass for flat panel displays,
The glass has a weight ratio of 54-68% SiO ₂ , 10.8-17.1% Al ₂ O ₃ , 7.6-12.5% B ₂ O ₃ , 0.2-1.8% MgO, 4.2-8% CaO, 0.6-7.1 An alkali-free glass comprising% SrO, 0.1-5% BaO, 0.2-1% ZnO, 0.01-1.54% ZrO ₂ and 0.2-1.3% SnO + SnO ₂ .
The method of claim 1,
Alkali-free glass, characterized in that the weight ratio of MgO + SrO + BaO in the glass is 0-12%.
The method of claim 1,
The light transmittance of the said glass is 93-97, The alkali free glass characterized by the above-mentioned.
The method of claim 1,
Strain point of the glass is alkali-free glass, characterized in that 650 ~ 685 ℃.
The method of claim 1,
The coefficient of thermal expansion of the glass is an alkali-free glass, characterized in that 30 × 10 ^-7 / ℃ to 40 × 10 ^-7 / ℃ in the range of 0 ~ 300 ℃.
The method of claim 3, wherein
The liquidus temperature of the glass is 1110 ~ 1210 ℃ alkali-free glass, characterized in that.
The method of claim 1,
Alkali free glass, characterized in that the density of the glass is 2.300 ~ 2.550g / cm ³ .
As a method of manufacturing the alkali-free glass of claim 1,
(1) The components of the glass raw material are 54 to 67% of SiO ₂ , 13 to 18% of Al ₂ O ₃ , 7 to 12% of B ₂ O ₃ , 0 to 1.8% of MgO, and 3 to 10 by weight. % CaO, 0.2-8% SrO, 0.1-7% BaO, 0.001-1.5% ZnO, 0.001-1.0% ZrO ₂ and 0.01-1.0% purifying agent;
(2) The raw material according to the step (1) is reacted intact for 4 hours in the temperature range of 1500 ~ 1620 ° C to obtain a glass solution in the first container of the non-metal refractory material, the glass solution to the second container Introduced;
(3) the glass solution in the second vessel was insulated at 1640 ° C. for 40-75 minutes and at 1600 ° C. for 40-120 minutes;
(4) The solution obtained in the step (3) is introduced into a metal mold and cooled to form a flat plate and then annealed to produce the alkali-free glass, characterized in that it comprises the step of obtaining the alkali-free glass Way.